A standard field chopper has a housing centered on an axis and having a radially open input and a radially open output spaced angularly therefrom. A cutter drum rotatable in the housing about the axis has a pair of end plates transverse of the axis and having axially oppositely, directed faces confronting the respective intakes and a plurality of blades secured to and between the end plates and having cutting edges defining on rotation of the drum an orbit centered on the axis. The material to be chopped--fresh or dry fodder, hay, corn, or the like--is fed into the input where it is chopped up by the rapidly rotating blades and expelled as pieces from the output.
Such an arrangement is relatively efficient when used with hard crop, such as bark chips or corn, but can jam up when used to chop and convey lighter material such as hay or limp crop.
Thus it has been suggested in German Pat. No. 955,370, German utility model 1,986,843, German patent document 2,612 092, and Czechoslovakian Pat. No. 120,420 to mount air vanes on the rotor which form a powerful air stream that enhances flow out of the housing. Such vanes are normally mounted on the end plates and the housing is formed with axially open air intakes confronting the vaned portions of the end plates Thus these vanes form an axial-input radial-output fan, making the chopper capable of handling and conveying difficult materials.
The problem is that choppers thus equipped are less efficient when dealing with heavier crop than those without vanes Nonetheless the vaned arrangement is usually selected so that the user can chop all types of materials, even though with some materials the efficiency is reduced